This invention relates to generally to wells used in the production of fluids such as oil and gas. More specifically, this invention relates to a method and system for perforating and performing other operations in wells.
Different operations are performed during the drilling and completion of a subterranean well, and also during the production of fluids from subterranean formations via the completed well. For example, different downhole operations are typically performed at some depth within the well, but are controlled at the surface.
A perforating process is one type of downhole operation that is used to perforate a well casing. A conventional perforating process is performed by placing a perforating tool (i.e., perforating gun) in a well casing, along a section of the casing proximate to a geological formation of interest. The perforating tool carries shaped charges that are detonated using a signal transmitted from the surface to the charges. Detonation of the charges creates openings in the casing and concrete around the casing, which are then used to establish fluid communication between the geological formation, and the casing.
Another example of a downhole operation is the setting of packers within the well casing to isolate a particular section of the well or a particular geological formation. In this case, a packer can be placed within the well casing at a desired depth, and then set by a setting tool actuated from the surface. Other exemplary downhole operations include the placement of bridge plugs, and cutting operations.
In the past downhole operations have been controlled by transmission of signals from surface equipment to downhole equipment located in the well. This control method typically requires a signal transmission conduit to provide signal communication between the surface equipment and the downhole equipment. For example, electric lines are used to transmit electronic signals, and hydraulic lines are used to transmit hydraulic signals.
Conventional signal transmission conduits are expensive to install in a well, and must often be discarded after the well is completed. In addition, signal transmission conduits are subject to rough handling, and must operate in harsh conditions such as in corrosive fluids at high temperatures and pressures. Accordingly, signal transmission conduits can be damaged, and problems can occur during signal transmission from the surface equipment to the downhole equipment. It would be desirable to be able to control downhole operations without the necessity of signal transmission conduits to the surface.
The present invention is directed to a method and system for perforating and performing various operations in wells in which signal transmission conduits to the surface are not required.
In accordance with the present invention a method and a system for performing various operations in wells are provided. The method, broadly stated, includes the steps of providing a process tool configured to perform an operation in a well, and placing the tool at a required depth within the well. For placing the tool at the required depth, the tool can be conveyed on a casing of the well (e.g., casing conveyed), conveyed on a tubing string of the well (e.g., tubing conveyed), or conveyed on an external conveyance mechanism, such as a wire line or a coil tubing placed in the well. In addition, well logs and a logging tool can be used to place the tool in the well at the required depth.
The method also includes the steps of placing a reader device in the well configured to control the tool, and then transporting an identification device through the well past the reader device to actuate the reader device and control the tool. The identification device can comprise a radio identification device configured to receive rf transmission signals from the reader device, and to transmit a unique code signal to the reader device responsive to reception of the transmission signals. The reader device can comprise a transmitter configured to provide the rf transmission signals, and a receiver configured to receive the unique code signal from the identification device.
The identification device includes a programmable memory device, such as a transceiver chip for storing and generating the unique code signal. The identification device can be configured as a passive device, as an active device, or as a passive device which can be placed in an active state by transmission of signals through well fluids. In addition, the identification device can be transported through a casing of the well, or alternately through a tubing string of the well, using a transport mechanism, such as a pump, a robot, a parachute or gravity.
In addition to the transmitter and the receiver, the reader device includes a control circuit configured to generate control signals for controlling the tool responsive to reception of the unique code signal from the identification device. The reader device control circuit includes a controller which comprises one or more memory devices programmable to look for the unique code signal. The reader device control circuit also includes a power source, such as a battery, and a telemetry circuit for transmitting control signals to the tool. The reader device can be mounted to a collar configured to allow rf signals to freely travel between the reader device and the identification device. The collar can be attached to the process tool, to the well casing, or to the tubing string of the well.
In a first embodiment the tool comprises a casing conveyed perforating tool placed at the required depth in the well, and a perforating process is performed as the identification device is transported past the perforating tool, and transmits the unique rf code signal to the reader device. In a second embodiment the tool comprises a tubing conveyed packer setting tool placed at the required depth in the well, and a packer setting process is performed as the identification device is transported past the packer setting tool, and transmits the unique rf code signal to the reader device.
The system includes the process tool and the reader device placed at the required depth within the well. The system also includes the identification device, and the transport mechanism for transporting the identification device through the well casing, or alternately through the tubing string of the well.